I ran across this book and its sequels, The Weed That Strings the Hangman’s Bag, A Red Herring Without Mustard (and there are two more: I Am Half-Sick of Shadows and Speaking from Among the Bones) by reading an article in the The New York Times on the author who started writing when he was in his 70s. His character is an 11 year-old girl growing up on the family estate in England after the second world war, so the date is 1950 — quite a ways ago.
I was interested because Alan Bradley (the author) explained that Flavia just appeared in the middle of another book and demanded that he write her books. Good characters are like that although I will also give kudos to her perfectly dreadful older sisters.
Anyway, if you like murder mysteries and 11 year-old girls who are intrigued with poisons, then you won’t go wrong with Flavia de Luce!